1. Field of the Invention
The invention is concerned with a novel group of compositions. It more particularly relates to a grease composition comprising oil, hydroxy-containing soap thickener and borated hydroxy-containing esters and phosphorus and sulfur moities.
2. Discussion of the Prior Art
Alcohols are well known for their lubricity properties when formulated into lubricating oils and for their water scavenging characteristics when blended into fuels. The use of vicinal hydroxyl-containing alkyl carboxylates such as gylcerol monoolerate have also found widespread use as lubricity additives. U.S. Pat. No. 2,788,326 discloses some of the esters suitable for the present invention, e.g., gylcerol monooleate, as minor components of lubricating oil compositions. U.S. Pat. No. 3,235,498 discloses, among others, the same ester as just mentioned, as an additive to other oils. U.S. Pat. No. 2,443,578 teaches esters wherein the free hydroxyl is found in the acid portion, as for example, in tartaric acid.
The above patents, as are numerous others, are directed to the use of such esters as additives. Other patents, such as U.S. Pat. Nos. 2,798,083; 2,820,014; 3,115,519; 3,282,917 and 3,309,318 as well as an article by R. R. Barnes et al. entitled "Synthetic Ester Lubricants" in Lubrication Engineering, August, 1975, pp 454-457, teach lubricants prepared from polyhydric alcohols and acids containing no hydroxyl other than those associated with the acid function.
So far as is known, no effort has been made to employ the borated mixtures of this invention as lubricant additives in conjunction with metal hydroxy-containing soap thickener and phosphorus and sulfur moieties. No prior art is known that teaches or suggests the unexpected results obtained by combining the known additives mentioned herein with the particular thickener and the borate hydroxyesters of this invention.